You and I :

Marshall's wish has skewed him into an alternate timeline where he and Fionna never started dating. Can he win Fionna back before it's too late?

Marshall darted up immediately realizing that he was laying in bed. He looked around confused and noticed his phone was buzzing. He picked it up immediately.

"Speak."
"Marshall Lee." Prince Gumball said excited. "I need help and my help bailed on me so I'm going to ask you for a favor."
"What?"
"Well a good friend of mine asked if I could help him with his wedding and I need help finding a present and making the guest list."
"Sure pinky. Who's getting married."
"It's the royal wedding of Flame prince and Fionna."
"oh... wait the WHAT? Fionna's getting married?!"
"Yeah, You didn't hear? They've been dating for months he proposed to her last wee-"
"NO no no no no no NO! Gumball I'm coming to see you. This is serious and I need your brain to help me!"

Gumball was drawing on his chalk board as Marshall explained what had happened. All he remember was rapping and being angry. When Gumball withdrew from the chalkboard Marshall saw a timeline of everything since he and Fionna started dating up until he made the wish.
"Interesting. When you made the wish to the Fire spirit it spiraled out into an alternate timeline where you never interrupted that date with Flame prince. Essentially, You never did any of this. Lucky for you that means you never argued. I'm sorry."
"There has to be a way to win her back! I love her Gumball."
"How did you get her to fall in love with you the first time?"
"I sang her a song I never got around to finishing about us. She went crazy for it. It's still not done.
"Well I don't advocate stealing his fiancé but if you can finish that song it might help you." Marshall sighed.
"Whens the wedding..."
"You have 3 days."

Marshall hadn't slept or eaten in 2 days. He looked at every little thing that reminded him of Fionna in hopes that he could finish the song. His well of inspiration was running out. " I wanted you to tell me how...to tell me how." Marshall struggled with the words of his song. "I fly so high... Just to fall ...do-wn. No No NO. I just can't. I need Fionna... I've always needed Fionna. Such a warm smile. Maybe I can't work with Fiolee... Maybe I need a new song entirely. Mess with the tune around a bit." Schwable toddled into the room and barked. "Not now." Schwable growled and began to bark. He wasn't just barking though, there was a pattern to it. Marshall listened close for a minute. When the dog stopped Marshall got his base ready. " Maybe a little faster paced... change the words... Yeah... Schwable... Let's crash a wedding.

Everything was red and flaming as to be expected. Marshall went early to speak with Flame prince who was talking with his mother. Upon seeing Marshall Flame Prince came over to him and extended his hand.
"Yeah, I didn't get anyone to cast Flame protect on me so, No handshake."
"Understandable, I'm glad you could come to my wedding."
"Yeah... Yeah."
"And I see you brought your base. Are you performing for my wedding?"
"Ummm Well-"
"Flame Prince!" Cake called for him.
"I have to go see what Cake needs. I'll talk to you in a minute." Flame Prince waved bye and started over to Cake. Marshall looked around at the decorated hall and the people casted blue by Flame protect. A blue figure started approaching him, Gumball.
"Oh hey Pinky."
"You ready?"
"Yeah, I'm prepared for everyone here to hate me if this doesn't work."
"If you and Fionna really are perfect for each other then this should work." Marshall puffed up his cheeks and looked around again.
"What if I'm too late and she loves him. Am I willing to put her on the spot?"
"Well You have until she says I do to decide." Bells chimed in very loudly and the guards yelled to the masses.
"Everyone please take your seats in the royal wedding chapel! Everyone sit for the royal wedding."
"Showtime. I think I'll sit in the back. Wanna join me pinky?" Gumball smiled.
"Sure."

Marshall figitited quite a bit until they started to play 'Here comes the bride'. Fionna looked astonishing in her wedding dress and by the request of Flame Prince she wasn't wearing her hat. Her hair was in a ponytail and Marshall's jaw simply dropped.
"Marshall... Marshall Lee." Gumball whispered to him. "Try to pay attention. If you miss your window you could ruin everything."
" If I make my window I still ruin everything." Marshall sat with his eyes fixated on Fionna through the ceremony. He tried to listen for the opportunity but he continued to think if he was being selfish or if he was really doing this for Fionna. Would she be better off.

"If anyone has a reason why these two should not be wed,"

"Marshall." Gumball whispered.

"Let them speak now.."

"What are you waiting for?!"

"Or forever hold.."

"I can't Gumball... I can't so it."

"Their peace."

"STOP THE WEDDING!" Gumball jumped up and yelled. Everyone gasped and looked back a blush creeped across Fionna's face. "Fionna there is someone who loves you and has to say so."
"Gumball..."
"No Fionna... Not me." Marshall was too red to even move until Gumball motioned for him to. He grabbed his base and floated into the aisle. He was in the back directly facing Fionna and Flame Prince.
"Marshall...Lee.."
"Fionna... I."
"Enough!" Flame Prince flared up. "Was this your plan all along? To ruin my wedding?"
"Sorry, But there's something I have to do." He strummed his bass to a tune that honestly he was just now making up. He knew the words to the song but he didn't prepare it very well. He was winging it. Gumball crossed his fingers.

You and I

Fallen this way..

I miss you..

You can't say.

I was so far-from yooou..

You don't know -he story.

I wish I could-show yooou.

The way we used-to beee.

The times we had have gone away

You don't remember how we came,

to be but I guess that's okaaaay.

Just don't hurt me this way...

I look to the sky every daay

I hope you remember those daaays

I miss your smile and your waaays

Just don't hurt me this waay...

You and I,

So long ago

Were in love

Where'd that go?

You can stay with him Nooow

If you feel that he's riiight

I don't want to hurt yooou

Say the word and I'll take fliiight.

The times we had have gone away

You don't remember how we came,

to be but I guess that's okaaaay.

Just don't hurt me this way...

I look to the sky every daay

I hope you remember those daaays

I miss your smile and your waaays

Just don't hurt me this waay...

It seems so long ago since then

You warm world again and a-gain

You have this effect on me

why can't you see

that your hurting me, yeah~

The times we had have gone away

You don't remember how we came,

to be but I guess that's okaaaay.

Just don't hurt me this way...

I look to the sky every day

I hope you remember those daaays

I miss your smile and your waaays

Just don't hurt me this waay...

The times we had have gone away

You don't remember how we came,

to be but I guess that's okaaaay.

Just don't hurt me this way...

I look to the sky every daay

I hope you remember those daaays

I miss your smile and your waaays

Just don't hurt me this waay...

Marshall stood there for a moment slightly embarrassed until one person started clapping. Marshall looked up and saw it was Gumball, standing and clapping slowly. After him a few people started to clap as well and even Cake started to clap until the whole room was filled with joyous tears and applause. Fionna tipped toed down the aisle to talk to Marshall Lee.
"Marshall..."
"Fi..."
"You really... felt that way about me?"
"I still do..." Fionna wasn't sure exactly how to react but the denizens of the Flame kingdom were very unhappy about it. "Fionna. I love you." More gasps were let out through the audience and Flame Prince started down the aisle but stopped halfway through.
"Please leave my wedding Marshall Lee. You are unwelcomed here." Marshall gently grabbed Fionna's hand and she looked at him. He left a soft kiss on her knuckle.
"I'm sorry. I was too late." He put his bass on his back and left. Gumball followed close behind him.

Marshall was floating in Gumballs lab staring at the alternate time line that he had created. A few tears escaped him and sighed often. Gumball looked up at the vampire and sighed as well.
"Better than wondering 'what if'. You tried." There was a knock at the lab door and Gumball opened it.
"Hey." Marshall perked up hearing that voice. He looked into the doorway to see his blushing bunny had returned to him.
"Fi-Fionna."
"Marshall I can't explain it... I just fit better with you than Flame Prince... I feel like were connected." Marshall didn't move. "Marshall? Come on say something." Suddenly he pounced her, pinning her to the wall he gave her a sweet and longing kiss. When they broke apart he hug her tightly.
"Can I tell you something?"
"What?"
"I was so scared you wouldn't come back to me..."

:D How do you like season 2 so far?